In recent years, from the viewpoints of human and material adverse effects, such as decoloration and deterioration of articles or skin sunburn by exposure to the sunlight, and from the viewpoint of energy saving, such as air-conditioning load reduction, in not only architectural window glass, but also automotive, watercraft and aircraft ones, etc., there has been a drastically increasing need for a plate glass article with multiple functions, such as having ultraviolet reflection and absorption, etc. in addition to heat ray reflection and absorption.
Since the above-mentioned plate glass article with multiple functions is used as a window glass, normally there is a tendency that one having lighting (i.e., visible light transmission) is preferred. Thus, it is requested to have ultraviolet and infrared shieldings and the visible light transmission. Above all, when it is used as an automotive front windshield, it is requested to have ultraviolet and infrared shielding properties and a visible light transmittance of at least 70%.
In general, to produce such glass, it is made to contain Fe2O3 (total iron oxide) as a coloring agent in the glass composition and is provided with ultraviolet absorptive property by Fe2O3 (trivalent iron), infrared absorptive property by FeO (divalent iron), and ultraviolet absorptive property by CeO2 and TiO2. Normally, such glass becomes a colored glass due to containing coloring components. In recent years, there has been a high demand for a glass showing a green color. Therefore, the color tone of the glass is controlled by adjusting the content of each component and proportions of the corresponding components. Furthermore, the glass is prevented from lowering of the visible light transmittance by a degree more than need.
Japanese Patent No. 3086165 B2 (Patent Publication 1) discloses an ultraviolet and infrared absorptive, greenish glass containing as coloring raw materials 0.40-0.90 mass % Fe2O3, 1.0-2.5 mass % CeO2, 0.1-1.0 mass % TiO2, 0.0010-0.0400 mass % MnO, 0.0001-0.0009 mass % CeO2, 0.0001-0.0010 mass % Cr2O3, and 0-1 mass % SnO2, and having optical properties (at a thickness of 5 mm) that the visible light transmittance by illuminant A is at least 65%, the solar transmittance is 30-40%, and the ultraviolet transmittance is 10% or lower.
Japanese Patent No. 3900550 B2 (Patent Publication 2) discloses an ultraviolet absorptive green glass consisting essentially of a soda-lime-silica glass containing 0.45-0.491 mass % total iron in terms of Fe2O3 (the amount of divalent iron in terms of Fe2O3 is 30.5-32.0 mass % relative to 100 mass % of total iron in terms of Fe2O3), 1.09-1.2 mass % CeO2, 0.3-0.39 mass % TiO2, and 0-0.0003 mass % CoO. This green glass has optical properties (at a thickness of 6.0 mm) that the visible light transmittance by illuminant A is at least 70%, and the ultraviolet transmittance is 6.94% or lower.
Japanese Patent No. 3899531 B2 (Patent Publication 3), corresponding to U.S. Pat. No. 6,017,837 A, discloses an ultraviolet and infrared absorptive glass, which contains as coloring raw materials 0.60-0.85 mass % Fe2O3 (total iron oxide), 1.4-1.7 mass % CeO2, and 0-0.15 mass % TiO2, and is characterized by satisfying the following equation,(0.2×(CeO2)−0.04)≦(FeO/T-Fe2O3)≦(0.2×(CeO2)+0.08)wherein (CeO2) represents the mass % of CeO2, (FeO/T-Fe2O3) represents the mass ratio of FeO in terms of Fe2O3 to the total iron oxide (T-Fe2O3) in terms of Fe2O3. Furthermore, this glass has optical properties (at a thickness of 4 mm) that the visible light transmittance by illuminant A is at least 70%, the solar transmittance is less than 48%, and the ultraviolet transmittance is less than 24%.
Japanese Patent Application Examined Publication 7-121815 B2 (Patent Publication 4), corresponding to U.S. Pat. No. 5,214,008 A, discloses an infrared and ultraviolet absorptive, green glass, which contains as coloring raw materials 0.7-0.95 mass % Fe2O3 (total iron oxide) and 0.19-0.24 mass % FeO and is substantially free from TiO2 and CeO2. This glass has optical properties at a thickness of from 3.7 mm to 4.8 mm that the visible light transmittance exceeds 70%, the total solar energy transmittance is less than 44.5%, and the ultraviolet transmittance is less than 38%.
Japanese Patent Application Publication 9-48635 A (Patent Publication 5), corresponding to U.S. Pat. No. 6,017,836 A, discloses an ultraviolet and infrared absorptive glass containing as coloring raw materials 0.5-1.0 mass % total iron in terms of Fe2O3, in which the FeO/total iron oxide ratio is 0.20 to 0.40, 0.2-2.0 mass % CeO2, and 0-1.0 mass % TiO2. Due to containing 0.2-5.0 mass % B2O3, this glass is classified as an alkaliborosilicate glass. Furthermore, this glass has optical properties at a thickness of 4 mm that the visible light transmittance is at least 70%, and the solar transmittance is less than 48%, and the ultraviolet transmittance is less than 30%.